docs: def decrease_posts_count_after_post_unaproval(sender, instance, **kwargs):
      """ Decreases the member's post count after a post unaproval.
  
      This receiver handles the unaproval of a forum post: the posts count associated with the post's
      author is decreased.
      """
      if not instance.pk:
          # Do not consider posts being created.
          return
  
      profile, dummy = ForumProfile.objects.get_or_create(user=instance.poster)
  
      try:
          old_instance = instance.__class__._default_manager.get(pk=instance.pk)
      except ObjectDoesNotExist:  # pragma: no cover
          # This should never happen (except with django loaddata command)
          return
  
      if old_instance and old_instance.approved is True and instance.approved is False:
          profile.posts_count = F('posts_count') - 1
          profile.save()